FTA-Sensor: Combination of Force/Torque and Acceleration - Robotized Transcranial Magnetic Stimulation - page 105

Fig. 6.7 Recorded and fitted forces (upper row) and accelerations (lower row) during a full
rotation of joint 4

0
@

1
A

ð FT T V V Þ 1 c F x ð FT T IMU A Þ x

f g

F user ¼

ð FT T V V Þ 2 c F y ð FT T IMU A Þ y f g ; ð 6 : 11 Þ

and

ð FT T V V Þ 3 c F z ð FT T IMU A Þ z f g

0 1

ð FT T V V Þ 4 c M x ðð FT T IMU A f g Þ s Þ x
ð FT T V V Þ 5 c M y ðð FT T IMU A f g Þ s Þ y
ð FT T V V Þ 6 c M z ðð FT T IMU A f g Þ s Þ z

@ A

M user ¼

ð 6 : 12 Þ

to estimate the gravity compensated forces F user and torques M user , based on the
voltage readings V, the accelerations A, and the tool's gravity force f g and centroid s.

6.1.5 Data Acquisition for Evaluation of the FTA Sensor

In order to evaluate the FTA sensor's performance, we conduct a systematic
analysis starting with the estimation of the calibration error and stability. Subse-
quently, we test the accuracy of the gravity compensation based on accelerations.
Furthermore, we measure the latency of the FTA sensor which is important to